For the first five years of my wow existence I clicked the screen with my mouse. I have always completed the content that I set as my goal and would argue with players that stated that there is no comparison to playing completely keybound.
I would make statements like "whatever works better for that person".
I would keybind certain macros for certain fights that I felt I would need at a moments notice and kept a finger over that button for the majority of those given fights.
I had the opportunity to receive some very sound advice from some world ranked players and it kind of opened my eyes. I went out and bought a Razer Nostromo, spent a couple of very painful weeks resisting the urge to click the screen and now a full tier into MOP I have to say that I am completely a convert. So much that, knowing the difference in performance that it brought me, I really prefer not to play with others that I know hold on to playing the game with their mouse.
So, to open the proverbial can of worms, vote the poll, then please support why you feel your opinion on the matter is the right one.